Unfortunately, it is current limitation on both iOS and Android that the /userinfo API must be invoked in order for SDK to determine authentication status. Specifically for iOS, SDK is looking at "preferred_username" in the response of /userinfo API to be returned.

It is mandatory that we need to have that information to correctly validate and analyze the auth status; however, it is also something that we have in our plan to investigate further on actual needs of the entire /userinfo API request. Which I don't have any set-date or details on what we will do at the moment.